This disclosure relates to an engine control system and method used of using a low octane fuel in a Gasoline Direct-Injection Compression-Ignition (GDCI) engine.
Gasoline Direct Injection Compression Ignition (GDCI) is an engine combustion concept that has demonstrated itself as a means to operate a compression-ignition engine on gasoline with significantly higher efficiency than gasoline spark-ignition engines and much lower engine-out emissions of particulate matter (PM) and oxides of nitrogen (NOx) than diesel compression-ignition engines. The combustion process of GDCI is uniquely different than for diesel compression ignition combustion systems in that the fuel is completely injected before the start of combustion, creating a partially premixed fuel-air mixture. This also means that control of the combustion is reliant on more than simply the start of main injection (as with diesel fuel).
Desired ignition and combustion phasing in GDCI is controlled by manipulations to the injection event(s) as well as the thermodynamic state of the engine cylinder contents (temperature, pressure, and chemical composition). To ensure fast response control of this thermodynamic state across a wide range of engine speeds and loads, the typical GDCI engine uses sophisticated valvetrain and boost systems. While these systems increase the power density and controllability of the engine, they also increase its cost. For some markets and applications, there could be a significant need for a low-cost high-efficiency version of GDCI which can operate on less processed low octane fuels.